<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>padding</title>
    <style>
        .box{
            width: 200px;
            height: 200px;
            background-color: pink;
        }
        .damao{
            background-color: #B61D1D;
            padding-left: 20px;
            padding-top: 30px;
        }
    </style>
</head>
<body>
<div class="box">
    对于padding来说，子盒子宽度继承于父盒子的宽度，高度由子盒子的内容撑起
    <div class="damao">123</div>
</div>
</body>
</html>